1. Field of the Invention
The present invention relates to a technology of a position detection apparatus having a signal line along which bit arrays are created in a direction determined in advance to serve as the direction of the signal line.
2. Description of the Related Art
In an image taking apparatus such as a digital camera, it is necessary to detect the position of a lens by typically execution of an AF (Auto Focus) control. In the process of detecting the position of the lens, however, an absolute-type encoder for detecting an absolute position is used. The absolute-type encoder typically detects an absolute position by carrying out parallel communications from a number of signal lines which are laid in parallel to each other.
With the absolute-type encoder, however, the resolution of the lens-position detection is determined by the number of signal lines. Thus, the absolute-type encoder raises a problem that the number of signal lines needs to be increased if a high resolution is required.
A technology disclosed in Japanese Patent Laid-Open No. 2002-277282 (hereinafter referred to as Patent Document 1) has been proposed as a technology for solving the problem described above. In accordance with the proposed technology, information on a detected absolute position is conveyed as typically serial data of 10 bits along a signal line. In this way, the number of signal lines can be sustained at a small value.